Wow, Ctrl+P has now started to open the proper print-interface with a preview! I've helped loads of people over the years complaining about printing in Fx vs Chrome. It used to be so in Fx that selecting Print from the menu opened an interface for printing (ala Chrome), but pressing Ctrl+P just opened standard OS print dialog. So power users never saw the nice print preview.
I seem to remember the controls for page fit being a little better with the old print preview, but my real complaint is with websites that don't scale well to print rather than Firefox's method of printing them.